WordPress at a glance
filter is not described

found_posts_query filter-hook . WP 2.1.0

Filters the query to run for retrieving the found posts.

Usage

add_filter( 'found_posts_query', 'filter_function_name_612', 10, 2 );
function filter_function_name_612( $found_posts, $this ){
	// filter...

	return $found_posts;
}
$found_posts(string)
The query to run to find the found posts.
$this(WP_Query)
The WP_Query instance (passed by reference).

Where the hook is called

WP_Query::set_found_posts()
found_posts_query
wp-includes/class-wp-query.php 3033
$this->found_posts = $wpdb->get_var( apply_filters_ref_array( 'found_posts_query', array( 'SELECT FOUND_ROWS()', &$this ) ) );

Where the hook is used (in WP core)

Does not used.